Bacterial Colonization on Endoscopic Materials and Surgical Field Without Infections After Transoral Endoscopic Thyroidectomy

INTRODUCTION

Our aim was to determine whether bacteria contamination occurred within the surgical field or on endoscopic equipment during surgery using the transoral endoscopic thyroidectomy vestibular approach (TOETVA).

MATERIALS AND METHODS

Participants were recruited from patients planned for TOETVA between May 2017 and December 2019. Bacterial samples were taken before and at the conclusion of the TOETVA procedure. The preoperative and postoperative samples were taken from the endoscopic materials and inferior oral vestibulum using a sterile flocked swab.

RESULTS

The study resulted in 480 samples (80 TOETVAs). No vestibular, port site, or neck infections occurred in any of the patients. Three (3.7%) out of 80 patients developed postoperative fever. Our results show different microbial communities during TOETVA. The most prevalent species detected were Streptococcus species. Multivariate logistic regression analyses revealed that the degree of contamination depended on the sampling site (inferior vestibulum > equipment) (P=0.03). In addition, the abundance of bacteria was affected by operative time (P=0.013). There were no significant differences observed in isolation frequencies of bacteria in malignancy (P=0.34).

CONCLUSIONS

TOETVA surgery is categorized as a "clean-contaminated" operation. A swab identified the common colonizers of oral microbiota on the endoscopic equipment and within the surgical field.

Enhanced mitigation of inhalable particles and fine particle-bound PAHs from a novel hazardous waste-power plant candidate

Emissions of the inhalable particle (dp < 10 μm, PM10) and their harmful compositions from combustion sources have high potential on health risk with nearly no regulation. This study investigates the particle size distribution (PSD), as well as the removal mechanism of PM10 and fine particle (FP)-bound polycyclic aromatic hydrocarbons (PAHs) from the flue gas of a hazardous waste thermal treatment system. It has ultralow regulated emission and becomes a candidate of power generation module. A series of the advanced scrubbers, cyclonic demister, and baghouse was equipped for multi-pollutant control. The moderate or intense low oxygen dilution (MILD) combustion effectively inhibited the PM2.5 generation by volumetric oxidation. Advanced scrubbers removed PM1, PM2.5, and PM10 by 85.24, 68.68, and 97.60%, respectively, which achieved by local supersaturation, heterogeneous condensation of water vapor, and the growth of fine PM. Moreover, the scrubbers effectively scavenged the course PM10 containing the high-molecular-weight PAH homologs onto the water phase but promoted the condensation and absorption of the lighter homologs onto the fine particle surface (dp ∼5.3 μm). The size window (dp = 0.3-1.0 μm) of the minimum efficiency reporting value of a BH filtration led to the peak of FP-PAH mass and BaP equivalent (BaPeq) toxicity at dp = 0.1-0.4 and 0.1-0.8 μm, respectively. Consequently, the synergy of MILD combustion and the SCB-CYC-BH system effectively inhibited the PM2.5, PM10, PM2.5-PAHs, and FP-PAH levels from a waste thermal treatment process and further mitigated the potential health risk.

Comparison of EMG amplitudes recorded by ipsilateral and contralateral electrodes placement during using trans-thyroid cartilage recording method in thyroid surgery

Objectives

The feasibility and reliability of trans-thyroid cartilage EMG recording method (TCERM) during intraoperative monitoring (IONM) of the recurrent laryngeal nerve (RLN) in thyroid surgery have been established. This study compared two different recording electrode placements on the ipsi-lateral and contra-lateral lamina of the thyroid cartilage (TC).

Methods

Fifty consecutive patients undergoing total thyroidectomy with 100 RLNs at risk were enrolled. Two paired subdermal needle electrodes were inserted into the subperichondrium of the bilateral TC lamina to record electromyography (EMG) signals. The channel leads from the TC electrodes were connected to the patient interface with two different modes. In A-mode, the electrode leads were placed ipsi-laterally, and channel 1 monitored the left RLN and channel 2 monitored the right RLN respectively. In B-mode, the electrode leads were placed contra-laterally, and channels 1 and 2 simultaneously monitored the same side of the RLN. The amplitudes of four EMG signals (V1-R1-R2-V2) recorded by A-mode and B-mode were compared.

Results

All EMG amplitudes of V1-R1-R2-V2 signals recorded with B-mode were all above 500μV and significantly higher than those with A-mode (p<0.001). No false loss of signal, electrode dislodgement, or needle-related complications were noted during IONM. Postoperatively, all patients had symmetrical vocal cord movement. Lower EMG amplitudes were observed in older and male patients. Histopathology and laterality showed no significant differences in EMG amplitude.

Conclusion

During using TCERM in thyroid surgery, the recording electrodes should be placed contra-laterally on the TC lamina. This approach ensures high and stable EMG signals, which are important for high-quality IONM of the RLN.

Bilayer osteochondral graft in rabbit xenogeneic transplantation model comprising sintered 3D-printed bioceramic and human adipose-derived stem cells laden biohydrogel

Reconstruction of severe osteochondral defects in articular cartilage and subchondral trabecular bone remains a challenging problem. The well-integrated bilayer osteochondral graft design expects to be guided the chondrogenic and osteogenic differentiation for stem cells and provides a promising solution for osteochondral tissue repair in this study. The subchondral bone scaffold approach is based on the developed finer and denser 3D β-tricalcium phosphate (β-TCP) bioceramic scaffold process, which is made using a digital light processing (DLP) technology and the novel photocurable negative thermo-responsive (NTR) bioceramic slurry. Then, the concave-top disc sintered 3D-printed bioceramic incorporates the human adipose-derived stem cells (hADSCs) laden photo-cured hybrid biohydrogel (HG + 0.5AFnSi) comprised of hyaluronic acid methacryloyl (HAMA), gelatin methacryloyl (GelMA), and 0.5% (w/v) acrylate-functionalized nano-silica (AFnSi) crosslinker. The 3D β-TCP bioceramic compartment is used to provide essential mechanical support for cartilage regeneration in the long term and slow biodegradation. However, the apparent density and compressive strength of the 3D β-TCP bioceramics can be obtained for ~ 94.8% theoretical density and 11.38 ± 1.72 MPa, respectively. In addition, the in vivo results demonstrated that the hADSC + HG + 0.5AFnSi/3D β-TCP of the bilayer osteochondral graft showed a much better osteochondral defect repair outcome in a rabbit model. The other word, the subchondral bone scaffold of 3D β-TCP bioceramic could accelerate the bone formation and integration with the adjacent host cancellous tissue at 12 weeks after surgery. And then, a thicker cartilage layer with a smooth surface and uniformly aligned chondrocytes were observed by providing enough steady mechanical support of the 3D β-TCP bioceramic scaffold.

Exosomes Derived from Hypoxia-Cultured Human Adipose Stem Cells Alleviate Articular Chondrocyte Inflammaging and Post-Traumatic Osteoarthritis Progression

Osteoarthritis (OA) is the most common age-related degenerative joint disease. Inflammaging, linking inflammation and aging, is found in senescent cells with the secretions of matrix-degrading proteins and proinflammatory cytokines. The senescence-associated secretory phenotype (SASP) plays a very important role in OA progression. However, there remains no effective way to suppress OA progression, especially by suppressing inflammaging and/or the chondrocyte SASP. Recent studies have shown that exosomes derived from hypoxia-cultured BMSCs can regenerate cartilage in OA animal models. Some reports have further indicated that exosomes secreted from MSCs contribute to the efficacy of MSC therapy in OA. However, whether hypoxia-cultured ADSC-secreted exosomes (hypoxia-ADSC-Exos) can alleviate the chondrocyte SASP or OA progression remains unclear. Accordingly, we hypothesized that hypoxia-ADSC-Exos have a beneficial effect on the normal functions of human articular chondrocytes (HACs), can attenuate the SASP of OA-like HACs in vitro, and further suppress OA progression in rats. Hypoxia-ADSC-Exos were derived from ADSCs cultured in 1% O2 and 10% de-Exo-FBS for 48 h. The molecular and cell biological effects of hypoxia-ADSC-Exos were tested on IL1-β-induced HACs as OA-like HACs in vitro, and the efficacy of OA treatment was tested in ACLT-induced OA rats. The results showed that hypoxia-ADSC-Exos had the best effect on GAG formation in normal HACs rather than those cultured in normoxia or hypoxia plus 2% de-Exo-FBS. We further found that hypoxia-ADSC-Exos alleviated the harmful effect in OA-like HACs by decreasing markers of normal cartilage (GAG and type II collagen) and increasing markers of fibrous or degenerative cartilage (type I or X collagen), matrix degradation enzymes (MMP13 and ADAMT5), and inflammatory cytokines (TNFα and IL-6). More importantly, intra-articular treatment with hypoxia-ADSC-Exos suppressed OA progression, as evidenced by the weight-bearing function test and cartilage GAG quantification in ACLT rats. Moreover, through NGS and bioinformatic analysis, seven potential miRNAs were found in hypoxia-ADSC-Exos, which may contribute to regulating cellular oxidative stress and attenuating cell senescence. In summary, we demonstrated that hypoxia-ADSC-Exos, carrying potent miRNAs, not only improve normal HAC function but also alleviate HAC inflammaging and OA progression. The results suggest that hypoxia-ADSC-Exo treatment may offer another strategy for future OA therapy.

The role of the genomic mutation signature and tumor mutation burden on relapse risk prediction in head and neck squamous cell carcinoma after concurrent chemoradiotherapy

Personalized genetic profiling has focused on improving treatment efficacy and predicting risk stratification by identifying mutated genes and selecting targeted agents according to genetic testing. Therefore, we evaluated the role of genetic profiling and tumor mutation burden (TMB) using next-generation sequencing in patients with head and neck squamous cell carcinoma (HNSC). The relapse mutation signature (RMS) and chromatin remodeling mutation signature (CRMS) were explored to predict the risk of relapse in patients with HNSC treated with concurrent chemoradiotherapy (CCRT) with platinum-based chemotherapy. Patients in the high RMS and CRMS groups showed significantly shorter relapse-free survival than those in the low RMS and CRMS groups, respectively (p < 0.001 and p = 0.006). Multivariate Cox regression analysis showed that extranodal extension, CCRT response, and three somatic mutation profiles (TMB, RMS, and CRMS) were independent risk predictors for HNSC relapse. The predictive nomogram showed satisfactory performance in predicting relapse-free survival in patients with HNSC treated with CCRT.

Multimodal Analgesia with Local Wound Infiltration and Intravenous Parecoxib for Thyroidectomy

Background and objective: Adequate postoperative pain control is an important component to enhance recovery. Multimodal analgesia with various pain control techniques has been widely used to alleviate postoperative pain. The use of either wound infiltration or a superficial cervical plexus block has been reported to be effective for pain management after thyroid surgery. The present study evaluated the effect of multimodal analgesia using lidocaine wound infiltration combined with intravenous parecoxib for patients monitored after thyroidectomy. Materials and Methods: A total of 101 patients with a multimodal analgesia protocol being monitored after thyroidectomy were enrolled. After the induction of anesthesia, multimodal analgesia was performed through wound infiltration of 1% lidocaine and epinephrine at a ratio of 1:200,000 (5 μg/mL) combined 40 mg intravenous parecoxib before skin excision. Patients were divided into two groups for this retrospective analysis based on the injection dose of lidocaine they received. Patients in Group I (the control, n = 52) received a 5 mL injection solution, while those in Group II (the study, n = 49) received a 10 mL dosage in a time-sequential manner, in accordance with a previous clinical trial. The primary outcome was measuring postoperative pain intensity at rest, as well as during motion and coughing, which was measured at the postoperative anesthetic care unit (PACU) and on the first day after the operation (POD 1) in the ward. Pain intensity was assessed using a numerical rating scale (NRS). The secondary outcomes were postoperative adverse events including anesthetic-related side effects, as well as airway and pulmonary complications. Results: Most of the patients reported no pain or mild pain during the observation period. The patients in Group II had a lower pain intensity during motion than Group I (NRS 1.47 ± 0.89 vs. 1.85 ± 0.96, p = 0.043) when measured at the postoperative anesthetic care unit. Pain intensity during coughing was also significantly lower in the study group than in the control group (NRS 1.61 ± 0.95 vs. 1.96 ± 0.79, p = 0.049) when measured at the postoperative anesthetic care unit. There were no severe adverse events in either of the groups. Only one patient (1.9%) in Group I experienced temporary vocal palsy. Conclusions: The use of lidocaine with an equal volume of intravenous parecoxib provided comparable analgesia with minimal adverse events when monitoring thyroidectomy.

Growth Regulated Oncogene-α Upregulates TNF-α and COX-2 and Activates NOD1/RIPK2 mediated-MAPK Pathway in Head and Neck Squamous Cell Carcinoma

Purpose: The long-term prognosis and survival rate of patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) are poor, although the identification of specific biomarkers that reveal its nature and aggressiveness has improved it. Growth-related oncogene alpha (Groα) and NOD1 (nucleotide-binding oligomerization domain 1) can be used as prognosis markers to identify subgroups of HNSCC patients with low survival rates and as potential therapeutic targets for HNSCC patients. However, the mechanism associated with the Groα-mediated NOD pathway in HNSCC progression remains unclear. Method: Overall survival analysis and multiple-gene comparison were analyzed using Gene Expression Profiling Interactive Analysis (GEPIA). qRT-PCR and RT-PCR were used to analyze mRNA expression. Microarray, immunofluorescence staining or western blot analyses were carried out to detect protein expression. Results: Groα was significantly higher in the grade 4 HNSCC tumor tissues compared with that in grade 1-3 and healthy subjects. High expression of Groα, NOD1 and RIPK2 (receptor-interacting serine-threonine kinase 2) is correlated with survival rate in HNSCC patients. Treatment of SCC25 and OECM-1 cells with Groα increased the expression of NOD1 and RIPK2 in a concentration-dependent manner. The findings herein reveal the association of Groα, NOD1 and RIPK2 biomarkers with HNSCC carcinogenesis. Moreover, Groα is the major stimulus of inflammatory mediation and promotes TNF-α (tumor necrosis factor-α) and COX-2 (cyclooxygenase-2) expression in HNSCC. Groα induces TNF-α and COX-2 expression through regulation involving ERK (extracellular signal-regulated kinase)-, JNK (C-Jun N-terminal kinase)- and p38 MAPK (mitogen-activated protein kinase)-dependent signaling pathways. Conclusions: Our findings herein constitute the first evidence that Groα is important in HNSCC progression and metastasis via the NOD1-mediated MAPK pathway, suggesting a role for Groα and NOD1 in mediating metastasis and its potential as a therapeutic target.

Administration of neostigmine after tracheal intubation shortens time to successful intraoperative neuromonitoring during thyroid surgery: a randomized controlled trial

This prospective, randomized controlled trial evaluated the effect of neostigmine for intraoperative neuromonitoring (IONM) during thyroid surgery. Forty subjects undergoing thyroidectomy with IONM, randomized into neostigmine administration after tracheal intubation (Group N, n = 20) or control treatment with normal saline (Group C, n = 20), completed the trial. Electromyography amplitudes of the vagus nerve (V1) were recorded before thyroid dissection. The time from the initial V1 signal check to successful V1 stimulation was recorded. In Group N, all the patients had a successful V1 signal at the first check, whereas ten (50%) patients in Group C had a time delay between the initial V1 check and successful V1 (p < 0.001). The mean delay time among the delayed patients in Group C was 11.2 ± 1.4 min. The mean time from skin incision to successful V1 stimulation was significantly shorter in Group N than in Group C (15.4 ± 2.4 min vs. 19.9 ± 5.7 min, p = 0.003). In Groups N and C, the mean V1 amplitudes were 962.2 ± 434.5 μV vs. 802.3 ± 382.7 μV (p = 0.225), respectively, and the mean R1 amplitudes were 1240.0 ± 836.5 μV vs. 1023.4 ± 455.8 μV (p = 0.316), respectively. There was one bucking event in Group N. In conclusion, neostigmine administration immediately after tracheal intubation can be useful to reverse neuromuscular blockade for successful IONM in thyroid surgeries.

Proposals for Standardization of Intraoperative Facial Nerve Monitoring during Parotid Surgery

Intraoperative facial nerve monitoring (FNM) has been widely accepted as an adjunct during parotid surgery to facilitate identification of the facial nerve (FN) main trunk, dissection of FN branches, confirmation of FN function integrity, detection of FN injury and prognostication of facial expression after tumor resection. Although the use of FNM in parotidectomy is increasing, little uniformity exists in its application from the literature. Thus, not only are the results of many studies difficult to compare but the value of FNM technology is also limited. The article reviews the current literature and proposes our standardized FNM procedures during parotid surgery, such as standards in FNM setup, standards in general anesthesia, standards in FNM procedures and application of stimulus currents, interpretation of electrophysiologic signals and prediction of the facial expression outcome and pre-/post-operative assessment of facial expressions. We hope that the FNM standardized procedures will provide greater uniformity, improve the quality of applications and contribute to future research.

Enhancement of Osteoblast Function through Extracellular Vesicles Derived from Adipose-Derived Stem Cells

Adipose-derived stem cells (ADSCs) are a type of mesenchymal stem cell that is investigated in bone tissue engineering (BTE). Osteoblasts are the main cells responsible for bone formation in vivo and directing ADSCs to form osteoblasts through osteogenesis is a research topic in BTE. In addition to the osteogenesis of ADSCs into osteoblasts, the crosstalk of ADSCs with osteoblasts through the secretion of extracellular vesicles (EVs) may also contribute to bone formation in ADSC-based BTE. We investigated the effect of ADSC-secreted EVs (ADSC-EVs) on osteoblast function. ADSC-EVs (size ≤ 1000 nm) were isolated from the culture supernatant of ADSCs through ultracentrifugation. The ADSC-EVs were observed to be spherical under a transmission electron microscope. The ADSC-EVs were positive for CD9, CD81, and Alix, but β-actin was not detected. ADSC-EV treatment did not change survival but did increase osteoblast proliferation and activity. The 48 most abundant known microRNAs (miRNAs) identified within the ADSC-EVs were selected and then subjected to gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. The GO analysis revealed that these miRNAs are highly relevant to skeletal system morphogenesis and bone development. The KEGG analysis indicated that these miRNAs may regulate osteoblast function through autophagy or the mitogen-activated protein kinase or Ras-related protein 1 signaling pathway. These results suggest that ADSC-EVs enhance osteoblast function and can contribute to bone regeneration in ADSC-based BTE.

Safety Parameters of Quantum Molecular Resonance Devices During Thyroid Surgery: Porcine Model Using Continuous Neuromonitoring

OBJECTIVES

Quantum molecular resonance (QMR) devices have been applied as energy-based devices in many head and neck surgeries; however, research on their use in thyroid surgery is lacking. This study aimed to investigate the safety parameters of QMR devices during thyroidectomy when dissection was adjacent to the recurrent laryngeal nerve (RLN).

METHODS

This study included eight piglets with 16 RLNs, and real-time electromyography (EMG) signals were obtained from continuous intraoperative neuromonitoring (C-IONM). QMR bipolar scissor (BS) and monopolar unit (MU) were tested for safety parameters. In the activation study, QMR devices were activated at varying distances from the RLN. In the cooling study, QMR devices were cooled for varying time intervals, with or without muscle touch maneuver (MTM) before contacting with the RLN.

RESULTS

In the activation study, no adverse EMG change occurred when QMR BS and MU were activated at distances of 2 mm or longer from the RLNs. In the cooling study, no adverse EMG change occurred when QMR BS and MU were cooled in 2-second intervals or immediately after MTM.

CONCLUSION

QMR devices should be carefully used when performing RLN dissection during thyroid surgery. According to the activation and cooling safety parameters in this study, surgeons can avoid RLN injury by following standard procedures when using QMR devices.

Intraoperative EMG recovery patterns and outcomes after RLN traction-related amplitude decrease during monitored thyroidectomy

OBJECTIVES

Traction injury is the most common type of recurrent laryngeal nerve (RLN) injury in thyroid surgery. Intraoperative neuromonitoring (IONM) facilitates early detection of adverse electromyography (EMG) effect, and this corrective maneuver can reduce severe and repeated nerve injury. This study aimed to evaluate intraoperative patterns and outcomes of EMG decrease and recovery by traction injury.

METHODS

644 patients received nerve monitored thyroidectomy with 1142 RLNs at risk were enrolled. Intermittent IONM with stimulating dissecting instrument (real-time during surgical procedure) and trans-thyroid cartilage EMG recording method (without electrode malpositioning issue) were used for nerve stimulation and signal recording. When an EMG amplitude showed a decrease of >50% during RLN dissection, the surgical maneuver was paused immediately. Nerve dissection was restarted when the EMG amplitude was stable.

RESULTS

44/1142 (3.9%) RLNs exhibited a >50% EMG amplitude decrease during RLN dissection and all (100%) showed gradual progressive amplitude recovery within a few minutes after releasing thyroid traction (10 recovered from LOS; 34 recovered from a 51-90% amplitude decrease). Three EMG recovery patterns were noted, A-complete EMG recovery (n=14, 32%); B-incomplete EMG recovery with an injury point (n=16, 36%); C-incomplete EMG recovery without an injury point (n=14, 32%). Patients with postoperative weak or fixed vocal cord mobility in A, B, and C were 0(0%), 7(44%), and 2(14%), respectively. Complete EMG recovery was found in 14 nerves, and incomplete recovery was found in another 30 nerves. Temporary vocal cord palsy was found in 6 nerves due to unavoidable repeated traction.

CONCLUSION

Early detection of traction-related RLN amplitude decrease allows monitoring of intraoperative EMG signal recovery during thyroid surgery. Different recovery patterns show different vocal cord function outcomes. To elucidate the recovery patterns can assist surgeons in the intraoperative decision making and postoperative management.

A Surgeon-Centered Neuromuscular Block Protocol Improving Intraoperative Neuromonitoring Outcome of Thyroid Surgery

BACKGROUND

Neuromuscular blocking agents provide muscular relaxation for tracheal intubation and surgery. However, the degree of neuromuscular block may disturb neuromuscular transmission and lead to weak electromyography during intraoperative neuromonitoring. This study aimed to investigate a surgeon-friendly neuromuscular block degree titrated sugammadex protocol to maintain both intraoperative neuromonitoring quality and surgical relaxation during thyroid surgery.

METHODS

A total of 116 patients were enrolled into two groups and underwent elective thyroid surgery with intraoperative neuromonitoring. All patients followed a standardized intraoperative neuromonitoring protocol with continuous neuromuscular transmission monitoring and received 0.6 mg/kg rocuronium for tracheal intubation. Patients were allocated into two groups according to the degree of neuromuscular block when the anterior surface of the thyroid gland was exposed. The neuromuscular block degree was assessed by the train-of-four (TOF) count and ratio. Patients in group I received sugammadex 0.25 mg/kg for non-deep neuromuscular block degree (TOF count = 1~4). Patients in group II were administered sugammadex 0.5 mg/kg for deep neuromuscular block degree (TOF count = 0). The quality of the intraoperative neuromonitoring was measured using the V₁ electromyography (EMG) amplitude. An amplitude less than 500 μV and greater than 500 μV was defined as weak and satisfactory, respectively.

RESULTS

The quality of the intraoperative neuromonitoring was not different between groups I and II (satisfactory/weak: 75/1 vs. 38/2, P = 0.14). The quality of surgical relaxation was acceptable after sugammadex injection and showed no difference between groups [55/76 (72.3%) in group I vs. 33/40 (82.5%) in group II, P = 0.23].

CONCLUSIONS

This surgeon-centered sugammadex protocol guided by neuromuscular block degree (0.5 mg/kg for deep block and 0.25 mg/kg for others) showed comparably high intraoperative neuromonitoring quality and adequate surgical relaxation. The results expanded the practicality of sugammadex for precise neuromuscular block management during monitored thyroidectomy.

Necessity of Routinely Testing the Proximal and Distal Ends of Exposed Recurrent Laryngeal Nerve During Monitored Thyroidectomy

OBJECTIVES

Intraoperative neuromonitoring (IONM) is a useful tool to evaluate the function of recurrent laryngeal nerve (RLN) in thyroid surgery. This study aimed to determine the necessity and value of routinely testing the proximal and distal ends of RLN.

METHODS

In total, 796 patients undergoing monitored thyroidectomies with standardized procedures were enrolled. All 1346 RLNs with visual integrity of anatomical continuity were routinely stimulated at the most proximal (R2p signal) and distal (R2d signal) ends after complete RLN dissection. The EMG amplitudes between R2p and R2d signals were compared. If the amplitude of R2p/R2d ratio reduction (RPDR) was over 10% or loss of signal (LOS) occurred, the exposed RLN was mapped to identify the injured point. Pre- and post-operative vocal cord (VC) mobility was routinely examined with video-laryngofiberscope.

RESULTS

Nerve injuries were detected in 108 (8%) RLNs, including 94 nerves with incomplete LOS (RPDR between 13%-93%) and 14 nerves with complete LOS. The nerve injuries were caused by traction in 80 nerves, dissecting trauma in 23 nerves and lateral heat spread of energy-based devices in 5 nerves. Symmetric VC mobility was found in 72 nerves with RPDR ≤50%. The occurrence of abnormal VC mobility (weak or fixed) was 14%, 67%, 100%, and 100% among the different RPDR stratifications of 51%-60%, 61%-70%, 71%-80%, and 81-93%, respectively. Of the 14 nerves with complete LOS, all showed fixed VC mobility. Permanent VC palsy occurred in 2 nerves with thermal injury.

CONCLUSION

Routinely testing the proximal and distal ends of exposed RLN helps detect unrecognized partial nerve injury, elucidate the injury mechanism and determine injury severity. The procedure provides accurate information for evaluating RLN function after nerve dissection and should be included in the standard IONM procedure.

A comparison between cisatracurium and rocuronium-induced neuromuscular block on laryngeal electromyography recovery after neostigmine reversal in a porcine model

BACKGROUND

Inducing and reversing neuromuscular block is essential to a positive outcome of thyroid surgery, with intraoperative neuromonitoring (IONM) being used to decrease recurrent and superior laryngeal nerve injuries and improve vocal outcome. Neostigmine is a non-specific broad-spectrum and inexpensive reversal agent for neuromuscular blocking agents (NMBAs). The aim of this porcine study was to explore the effect of neostigmine on electromyography (EMG) signal recovery profile following the commonly used NMBAs, cisatracurium and rocuronium.

METHODS

Twelve piglets were allocated into two groups with six piglets in each group. When stable baseline EMG signals were obtained, a neuromuscular block was induced by intravenous cisatracurium 0.2 mg/kg (group C) or rocuronium 0.6 mg/kg (group R) for each piglet. We compared laryngeal EMG tracing with spontaneous recovery (control) and neostigmine (0.04 mg/kg) reversal for each group. The time course of real-time laryngeal EMG signals was observed for 30 min from NMBA injection. Effects of neostigmine on EMG signal were assessed at 50% EMG recovery and by the maximum neuromuscular block recovery degree from the baseline value.

RESULTS

Neostigmine shortened the recovery time to 50% EMG amplitude in both group C (16.5 [2.5] vs. 29.0 [2.0] min, P<0.01) and group R (16.5[2.5] vs. 26.5 [1.5] min, P<0.05) compared to spontaneous recovery, respectively. Neostigmine reversal also enhanced the maximum degree of EMG amplitude recovery in both group C (83.6 [5.1] vs. 47.2 [6.1] %, P<0.01) and group R (85.6 [18.2]vs. 57.1 [6.3] %, P<0.05) compared to spontaneous recovery, respectively. The reversal effect of neostigmine did not differ significantly between cisatracurium and rocuronium.

CONCLUSIONS

This porcine model demonstrated that neostigmine provides an adequate and timely IONM signal suppressed by both cisatracurium and rocuronium. These results can potentially expand the options for precision neuromuscular block management during IONM to improve vocal outcomes in thyroid surgery patients.

Improving Voice Outcomes After Thyroid Surgery - Review of Safety Parameters for Using Energy-Based Devices Near the Recurrent Laryngeal Nerve

Technological advances in thyroid surgery have rapidly increased in recent decades. Specifically, recently developed energy-based devices (EBDs) enable simultaneous dissection and sealing tissue. EBDs have many advantages in thyroid surgery, such as reduced blood loss, lower rate of post-operative hypocalcemia, and shorter operation time. However, the rate of recurrent laryngeal nerve (RLN) injury during EBD use has shown statistically inconsistent. EBDs generate high temperature that can cause iatrogenic thermal injury to the RLN by direct or indirect thermal spread. This article reviews relevant medical literatures of conventional electrocauteries and different mechanisms of current EBDs, and compares two safety parameters: safe distance and cooling time. In general, conventional electrocautery generates higher temperature and wider thermal spread range, but when applying EBDs near the RLN adequate activation distance and cooling time are still required to avoid inadvertent thermal injury. To improve voice outcomes in the quality-of-life era, surgeons should observe safety parameters and follow the standard procedures when using EBDs near the RLN in thyroid surgery.

Varied Recurrent Laryngeal Nerve Course Is Associated with Increased Risk of Nerve Dysfunction During Thyroidectomy: Results of the Surgical Anatomy of the Recurrent Laryngeal Nerve in Thyroid Surgery Study, an International Multicenter Prospective Anatomic and Electrophysiologic Study of 1000 Monitored Nerves at Risk from the International Neural Monitoring Study Group

Background: The recurrent laryngeal nerve (RLN) can be injured during thyroid surgery, which can negatively affect a patient's quality of life. The impact of intraoperative anatomic variations of the RLN on nerve injury remains unclear. Objectives of this study were to (1) better understand the detailed surgical anatomic variability of the RLN with a worldwide perspective; (2) establish potential correlates between intraoperative RLN anatomy and electrophysiologic responses; and (3) use the information to minimize complications and assure accurate and safe intraoperative neuromonitoring (IONM). Methods: A large international registry database study with prospectively collected data was conducted through the International Neural Monitoring Study Group (INMSG) evaluating 1000 RLNs at risk during thyroid surgery using a specially designed online data repository. Monitored thyroid surgeries following standardized IONM guidelines were included. Cases with bulky lymphadenopathy, IONM failure, and failed RLN visualization were excluded. Systematic evaluation of the surgical anatomy of the RLN was performed using the International RLN Anatomic Classification System. In cases of loss of signal (LOS), the mechanism of neural injury was identified, and functional evaluation of the vocal cord was performed. Results: A total of 1000 nerves at risk (NARs) were evaluated from 574 patients undergoing thyroid surgery at 17 centers from 12 countries and 5 continents. A higher than expected percentage of nerves followed an abnormal intraoperative trajectory (23%). LOS was identified in 3.5% of NARs, with 34% of LOS nerves following an abnormal intraoperative trajectory. LOS was more likely in cases of abnormal nerve trajectory, fixed splayed or entrapped nerves (including at the ligament of Berry), extensive neural dissection, cases of cancer invasion, or when lateral lymph node dissection was needed. Traction injury was found to be the most common form of RLN injury and to be less recoverable than previous reports. Conclusions: Multicenter international studies enrolling diverse patient populations can help reshape our understanding of surgical anatomy during thyroid surgery. There can be significant variability in the anatomic and intraoperative characteristics of the RLN, which can impact the risk of neural injury.

How the Severity and Mechanism of Recurrent Laryngeal Nerve Dysfunction during Monitored Thyroidectomy Impact on Postoperative Voice

Simple Summary

Recurrent laryngeal nerve (RLN) dysfunction remains a major source of morbidity after thyroid surgery. Intraoperative neuromonitoring can qualify and quantify RLN function according to the laryngeal electromyography (EMG) response evoked by electrical stimulation of the RLN. To the best of our knowledge, this is the first report to discuss the severity and mechanism of RLN dysfunction and postoperative voice in patients who have received monitored thyroidectomy. For optimal voice and swallowing outcomes after thyroid surgery, thermal injury must be avoided, especially when using energy-based devices, and mechanical injury must be identified early to avoid a more severe dysfunction. Adherence to standard intraoperative neuromonitoring (IONM) procedures for thyroid surgery is suggested, including standard procedures for acquiring and interpreting intraoperative RLN signals, for identifying and classifying RLN injury mechanisms, for performing laryngeal examinations and comprehensive voice assessments (subjective and objective voice analysis) before and after surgery, and for performing standard follow-up procedures.

Abstract

Intraoperative neuromonitoring can qualify and quantify RLN function during thyroid surgery. This study investigated how the severity and mechanism of RLN dysfunction during monitored thyroid surgery affected postoperative voice. This retrospective study analyzed 1021 patients that received standardized monitored thyroidectomy. Patients had post-dissection RLN(R2) signal <50%, 50–90% and >90% decrease from pre-dissection RLN(R1) signal were classified into Group A-no/mild, B-moderate, and C-severe RLN dysfunction, respectively. Demographic characteristics, RLN injury mechanisms(mechanical/thermal) and voice analysis parameters were recorded. More patients in the group with higher severity of RLN dysfunction had malignant pathology results (A/B/C = 35%/48%/55%, p = 0.017), received neck dissection (A/B/C = 17%/31%/55%, p < 0.001), had thermal injury (p = 0.006), and had asymmetric vocal fold motion in long-term postoperative periods (A/B/C = 0%/8%/62%, p < 0.001). In postoperative periods, Group C patients had significantly worse voice outcomes in several voice parameters in comparison to Group A/B. Thermal injury was associated with larger voice impairments compared to mechanical injury. This report is the first to discuss the severity and mechanism of RLN dysfunction and postoperative voice in patients who received monitored thyroidectomy. To optimize voice and swallowing outcomes after thyroidectomy, avoiding thermal injury is mandatory, and mechanical injury must be identified early to avoid a more severe dysfunction.

Investigation of potential neuropharmacological activity of neostigmine-glycopyrrolate for intraoperative neural monitoring in thyroid surgery

Intraoperative neuromonitoring (IONM) is frequently used in thyroid surgery to reduce recurrent laryngeal nerve injury. The use of neuromuscular blockade agent to facilitate tracheal intubation, is a common cause of IONM failure. We performed a retrospective analysis to assess the efficacy of neostigmine-glycopyrrolate as a neuromuscular blockade reversal agent for IONM during thyroid surgery. Rocuronium (0.6 mg/kg) was administered for muscle relaxation. Neostigmine (2 mg) and glycopyrrolate (0.4 mg) were administered immediately after intubation. Cricothyroid muscle-twitch response upon external branch of superior laryngeal nerve stimulation and electromyography amplitudes of vagal and recurrent laryngeal nerves before (V1, R1) and after thyroid resection (V2, R2) were recorded. Fifty patients (23 males, 27 females) were included in the analysis. The diagnoses comprised 43 papillary thyroid carcinomas and seven benign diseases. The mean time between rocuronium injection and neostigmine-glycopyrrolate injection was 5.1 ± 1.2 min, and the mean time from neostigmine-glycopyrrolate injection to successful cricothyroid muscle twitching upon external branch of superior laryngeal nerve stimulation was 21.0 ± 4.5 min. All patients had V1 and R1 amplitudes of more than 500 μV each, with mean V1 and R1 amplitudes of 985.3 ± 471.6 μV and 1177.2 ± 572.7 μV, respectively. Neostigmine-glycopyrrolate was effectively used as a neuromuscular blockade reversal agent for IONM in thyroid surgeries without a significant increase in bucking events. Administration of neostigmine-glycopyrrolate immediately after intubation can be recommended for successful NMB reversal to facilitate IONM during thyroid surgery.

Low Dose of Lenvatinib Treatment for Patients of Radioiodine-Refractory Differentiated Thyroid Carcinoma - A Real-World Experience

Background

Lenvatinib treatment of 24 mg/day for radioiodine-refractory differentiated thyroid carcinoma (RRDTC) patients was almost intolerable, with high rates of dose reduction, interruption and discontinuation. Balancing treatment safety with disease risks remains challenging, and the appropriate dosage remains unclear in Asia.

Patients and Methods

A total of 65 RRDTC patients treated with lenvatinib were retrospectively collected from Oct. 2015 to Jun. 2020 from two medical centers of South Taiwan. The drug tolerability, treatment efficacy and clinical outcomes were analyzed.

Results

Different doses of lenvatinib were initiated but ultimately maintained with a median dose of 10 mg/day within the first 3 months. The disease control rate reached 89.2%, including 24.6% partial response and 64.6% stable disease. Disease progression occurred in 10.8% of patients and increased to 40.0% at the end. Eventually, the treatment dose achieved a median progression-free survival (PFS) of 26.1 months (95% CI: 17.1-NA) with overall survival (OS) not reached yet (24.1~NA). Overall, the 48-month PFS rate was 35.6% (95% CI: 18.5–68.4) and 48-month OS was 54.3% (95% CI: 41.2–71.7). The dose was tolerable with a dose reduction rate of 44.6%, dose interruption rate of 40.0% and fewer high-graded adverse events. The drug discontinuation rate was only 3.1%. However, RRDTC patients with bone metastasis or maximal dose exposure to RAI (≥600 mCi) may have less efficacy to the low maintenance dose treatment.

Conclusion

Assessing treatment intensity, safety and efficacy, low-dose lenvatinib treatment was well tolerated by RRDTC patients and displayed acceptable drug efficacy and outcomes.

Drawbacks of neural monitoring troubleshooting algorithms in transoral endoscopic thyroidectomy

INTRODUCTION

The application of intraoperative neural monitoring (IONM) trouble-shooting algorithms procedures in transoral endoscopic thyroidectomy vestibular approach (TOETVA) was investigated.

METHODS

Loss of signal (LOS) is defined as a loss of the primary electromyographic (EMG) normal biphasic waveform with reduced amplitude response to less than 100μV with a stimulation level intensity of 1-2mA. A systematic review of the IONM system at LOS was covered methodically: (i) correct endotracheal tube verification, (ii) stimulation of the recurrent laryngeal nerve (RLN) at entry point, (iii) ipsilateral or contralateral vagal nerve (VN) stimulation, and (iv) laryngeal twitch (LT).

RESULTS

The function of 223 nerves at risk (NAR) was recorded with IONM. Twenty-seven (12%) NAR experienced a suspected LOS. LT could not be appreciated. In 15/27 (55%) cases, the application of the IONM trouble-shooting algorithm revealed upward displacement of the EMG tube (all orotracheal intubations). In 9 (4%) NAR, VN stimulation was not accomplished. In detail, there were n.5 left and n. 4 right VNs. Two VNs were ipsilateral, and 7 VNs contralateral. For EMG tube displacement, because the oral/nasal area is included in the aseptic field, it is less possible to re-check by the laryngoscope or fiberscope.

CONCLUSIONS

A limit for applying the IONM trouble-shooting algorithm to TOETVA is determined by (a) inability to appreciate the LT, (b) difficulty in stimulating the ipsilateral and contralateral VN, and (c) remodeling EMG endotracheal tube position. A modified IONM trouble-shooting algorithm for TOETVA is proposed.

Simvastatin Enhances the Chondrogenesis But Not the Osteogenesis of Adipose-Derived Stem Cells in a Hyaluronan Microenvironment

Directing adipose-derived stem cells (ADSCs) toward chondrogenesis is critical for ADSC-based articular cartilage regeneration. Simvastatin (SIM) was reported to promote both chondrogenic and osteogenic differentiation of ADSCs by upregulating bone morphogenetic protein-2 (BMP-2). We previously found that ADSC chondrogenesis is initiated and promoted in a hyaluronan (HA) microenvironment (HAM). Here, we further hypothesized that SIM augments HAM-induced chondrogenesis but not osteogenesis of ADSCs. ADSCs were treated with SIM in a HAM (SIM plus HAM) by HA-coated wells or HA-enriched fibrin (HA/Fibrin) hydrogel, and chondrogenic differentiation of ADSCs was evaluated. SIM plus HAM increased chondrogenesis more than HAM or SIM alone, including cell aggregation, chondrogenic gene expression (collagen type II and aggrecan) and cartilaginous tissue formation (collagen type II and sulfated glycosaminoglycan). In contrast, SIM-induced osteogenesis in ADSCs was reduced in SIM plus HAM, including mRNA expression of osteogenic genes, osteocalcin and alkaline phosphatase (ALP), ALP activity and mineralization. SIM plus HAM also showed the most effective increases in the mRNA expression of BMP-2 and transcription factors of SOX-9 and RUNX-2 in ADSCs, while these effects were reversed by CD44 blockade. HAM suppressed the levels of JNK, p-JNK, P38 and p-P38 in ADSCs, and SIM plus HAM also decreased SIM-induced phosphorylated JNK and p38 levels. In addition, SIM enhanced articular cartilage regeneration, as demonstrated by implantation of an ADSCs/HA/Fibrin construct in an ex vivo porcine articular chondral defect model. The results from this study indicate that SIM may be an enhancer of HAM-initiated MSC-based chondrogenesis and avoid osteogenesis.

Generating adipose stem cell-laden hyaluronic acid-based scaffolds using 3D bioprinting via the double crosslinked strategy for chondrogenesis

Bioprinting of most cell-laden hydrogel scaffolds with the required structural integrity, mechanical modulus, cell adhesion, cell compatibility, and chondrogenic differentiation are still significant issues that affect the application of bioinks in cartilage tissue engineering. This study focuses on constructing printable bioinks by combining adipose-derived stem cells (ADSCs), hyaluronic acid (HA)-based hydrogels and analyzing their ability to induce chondrogenesis using 3D bioprinting technology. First, biotinylated hyaluronic acid was synthesized via an adipic acid dihydrazide (ADH) linker with amide bond formation to form HA-biotin (HAB). Both HAB and the as-received streptavidin were mixed to form a partially cross-linked HA-biotin-streptavidin (HBS) hydrogel through noncovalent bonding. After that, the partially cross-linked HBS hydrogel was mixed with sodium alginate and subsequently printed to form the HBSA hydrogel 3D scaffolds using a bioprinter. Finally, the 3D scaffolds of the HBSA (HBS + alginate) hydrogel were submerged into CaCl₂ solution to achieve a stable 3D HBSAC (HBSA + Ca²⁺) hydrogel scaffold through ion transfer crosslinking. The physical-chemical characteristics of the hybrid bioink compositions have been evaluated to determine the desired 3D bioprinting structure. Cytotoxicity and chondrogenic differentiation were also assessed to confirm that the double cross-linked HBSAC hydrogel scaffold was useful for chondrogenic formation. The results showed that partially crosslinking the biotinylated HA-based hydrogel with streptavidin has a significant effect on printability and structural integrity. Morphological analysis of a suitable 3D printed HBSAC hydrogel scaffold showed visible pores with the desired shape and geometry. We have concluded that the HBSAC hydrogel possesses a favorable biocompatibility profile. The HBSAC hydrogel can also secrete significantly higher amounts of chondrogenic marker genes at day 5 and sulfated glycosaminoglycans (sGAGs) from days 7 to 14 compared to the HA hydrogel, as determined via quantitative real-time PCR assay and Alcian blue staining and the DMMB assay.

Superior Laryngeal Nerve Signal Attenuation Influences Voice Outcomes in Thyroid Surgery

OBJECTIVES/HYPOTHESIS

The objective was to identify whether injury of the external branch of the superior laryngeal nerve (EBSLN) or changes in EBSLN parameters after dissection during thyroidectomies correlate with changes in voice quality postoperatively.

STUDY DESIGN

Prospective multicenter case series.

METHODS

A prospective multicenter study was conducted on patients undergoing thyroidectomies with intraoperative nerve monitoring. Electromyography waveforms of EBSLN stimulation before (S1) and after superior pole dissection (S2) were evaluated using endotracheal tube (ETT) and cricothyroid intramuscular (CTM) electrodes. Voice outcomes were assessed using Voice-Related Quality of Life Surveys and Voice Handicap Index.

RESULTS

A total of 131 at-risk EBSLNs were evaluated in 80 patients. Two nerves showed loss of CTM twitch coupled with an absent S2 signal response. Complete EBSLN loss of signal was more likely with: 1) Cernea EBSLN anatomic classification Type 2B; 2) with a longer distance from the sternothyroid muscle insertion site; and 3) with larger lobar volumes (P < .05). Patients who experienced a more than 50% decrement in CTM amplitudes of S2 (n = 7) by CTM electrodes had a statistically significant decline in their voice outcomes compared to those who did not (n = 69) (P < .05).

CONCLUSIONS

Patients experienced worse voice outcomes when at least one EBSLN response amplitude decreased by more than 50% after dissection when measured by CTM needle electrodes. CTM needle electrodes have an ability to measure finer amplitude changes compared to ETT electrodes, may represent a safe method to deduce subtle EBSLN injuries, and may serve to optimize voice outcomes during thyroidectomy. CTM needle electrodes are safe and tolerated well.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:1436-1442, 2021.

New Developments in Anterior Laryngeal Recording Technique During Neuromonitored Thyroid and Parathyroid Surgery

A recurrent laryngeal nerve (RLN) injury resulting in vocal fold paralysis and dysphonia remains a major source of morbidity after thyroid and parathyroid surgeries. Intraoperative neural monitoring (IONM) is increasingly accepted as an adjunct to the standard practice of visual RLN identification. Endotracheal tube (ET) surface recording electrode systems are now widely used for IONM; however, the major limitation of the clinical use of ET-based surface electrodes is the need to maintain constant contact between the electrodes and vocal folds during surgery to obtain a high-quality recording. An ET that is malpositioned during intubation or displaced during surgical manipulation can cause a false decrease or loss of electromyography (EMG) signal. Since it may be difficult to distinguish from an EMG change caused by a true RLN injury, a false loss or decrease in EMG signal may contribute to inappropriate surgical decision making. Therefore, researchers have investigated alternative electrode systems that circumvent common causes of poor accuracy in ET-based neuromonitoring. Recent experimental and clinical studies have confirmed the hypothesis that needle or adhesive surface recording electrodes attached to the thyroid cartilage (transcartilage and percutaneous recording) or attached to the overlying neck skin (transcutaneous recording) can provide functionality similar to that of ET-based electrodes, and these recording methods enable access to the EMG response of the vocalis muscle that originates from the inner surface of the thyroid cartilage. Studies also indicate that, during surgical manipulation of the trachea, transcartilage, percutaneous, and transcutaneous anterior laryngeal (AL) recording electrodes could be more stable than ET-based surface electrodes and could be equally accurate in depicting RLN stress during IONM. These findings show that these AL electrodes have potential applications in future designs of recording electrodes and support the use of IONM as a high-quality quantitative tool in thyroid and parathyroid surgery. This article reviews the major recent developments of newly emerging transcartilage, percutaneous, and transcutaneous AL recording techniques used in IONM and evaluates their contribution to improved voice outcomes in modern thyroid surgery.

Correlation Between Objective and Subjective High-Pitched Voice Impairment in Patients After Thyroid Surgery

OBJECTIVES

High-pitched voice impairment (HPVI) is not uncommon in patients without recurrent laryngeal nerve (RLN) or external branch of superior laryngeal nerve (EBSLN) injury after thyroidectomy. This study evaluated the correlation between subjective and objective HPVI in patients after thyroid surgery.

METHODS

This study analyzed 775 patients without preoperative subjective HPVI and underwent neuromonitored thyroidectomy with normal RLN/EBSLN function. Multi-dimensional voice program, voice range profile and Index of voice and swallowing handicap of thyroidectomy (IVST) were performed during the preoperative(I) period and the immediate(II), short-term(III) and long-term(IV) postoperative periods. The severity of objective HPVI was categorized into four groups according to the decrease in maximum frequency (Fmax): <20%, 20-40%, 40-60%, and >60%. Subjective HPVI was evaluated according to the patient's answers on the IVST.

RESULTS

As the severity of objective HPVI increased, patients were significantly more to receive bilateral surgery (p=0.002) and have subjective HPVI (p<0.001), and there was no correlation with IVST scores. Among 211(27.2%) patients with subjective HPVI, patients were significantly more to receive bilateral surgery (p=0.003) and central neck dissection(p<0.001). These patients had very similar trends for Fmax, pitch range, and mean fundamental frequency as patients with 20-40% Fmax decrease (p>0.05) and had higher Jitter, Shimmer, and IVST scores than patients in any of the objective HPVI groups; subjective HPVI lasted until period-IV.

CONCLUSION

The factors that affect a patient's subjective HPVI are complex, and voice stability (Jitter and Shimmer) is no less important than the Fmax level. When patients have subjective HPVI without a significant Fmax decrease after thyroid surgery, abnormal voice stability should be considered and managed. Fmax and IVST scores should be interpreted comprehensively, and surgeons and speech-language pathologists should work together to identify patients with HPVI early and arrange speech therapy for them. Regarding the process of fibrosis formation, anti-adhesive material application and postoperative intervention for HPVI require more future research.

Training Courses in Laryngeal Nerve Monitoring in Thyroid and Parathyroid Surgery- The INMSG Consensus Statement

Intraoperative neural monitoring (IONM) is now an integral aspect of thyroid surgery in many centers. Interest in IONM and the number of institutions that perform monitored thyroidectomies have increased throughout the world in recent years. For surgeons considering the introduction of IONM in their practice, specific training in IONM devices and procedures can substantially shorten the learning curve. The International Neural Monitoring Study Group (INMSG) has been at the forefront of IONM technology and procedural adoption since the introduction of neural monitoring in thyroid and parathyroid surgery. The purpose of this document is to define the INMSG consensus on essential elements of IONM training courses. Specifically, this document describes the minimum training required for teaching practical application of IONM and consensus views on key issues that must be addressed for the safe and reliable introduction of IONM in surgical practice. The intent of this publication is to provide societies, course directors, teaching institutions, and national organizations with a practical reference for developing IONM training programs. With these guidelines, IONM will be implemented optimally, to the ultimate benefit of the thyroid and parathyroid surgical patients.

Informed Consent for Intraoperative Neural Monitoring in Thyroid and Parathyroid Surgery - Consensus Statement of the International Neural Monitoring Study Group

In the past decade, the use of intraoperative neural monitoring (IONM) in thyroid and parathyroid surgery has been widely accepted by surgeons as a useful technology for improving laryngeal nerve identification and voice outcomes, facilitating neurophysiological research, educating and training surgeons, and reducing surgical complications and malpractice litigation. Informing patients about IONM is not only good practice and helpful in promoting the efficient use of IONM resources but is indispensable for effective shared decision making between the patient and surgeon. The International Neural Monitoring Study Group (INMSG) feels complete discussion of IONM in the preoperative planning and patient consent process is important in all patients undergoing thyroid and parathyroid surgery. The purpose of this publication is to evaluate the impact of IONM on the informed consent process before thyroid and parathyroid surgery and to review the current INMSG consensus on evidence-based consent. The objective of this consensus statement, which outlines general and specific considerations as well as recommended criteria for informed consent for the use of IONM, is to assist surgeons and patients in the processes of informed consent and shared decision making before thyroid and parathyroid surgery.

Comparison of Surgical Complications Rates Between LigaSure Small Jaw and Clamp-and-Tie Hemostatic Technique in 1,000 Neuro-Monitored Thyroidectomies

Over the past decade, the use of neuromonitoring in thyroid surgery has become well established and is increasing accepted across the world. In addition, new developments in energy devices have significantly improved efficacy in achieving hemostasis in thyroid surgery. Few studies focused on the complication rates in energy device-assisted sutureless neuro-monitored thyroidectomy. This study investigates a novel LigaSure Small Jaw (LSJ) technique for sutureless thyroidectomy and compares the surgical complication rates between LSJ and conventional clamp-and-tie technique in one thousand consecutive neuro-monitored thyroidectomy patients. Five hundred patients received sutureless thyroidectomy performed with LSJ (Group L), and 500 patients received surgery performed with conventional clamp-and-tie technique (Group C). Complication rates of postoperative hematoma, hypocalcemia and recurrent laryngeal nerve (RLN) palsy were compared between groups. The overall complication rates of hematoma, hypocalcemia (temporary/ permanent), and RLN (temporary/ permanent) palsy were 0.9%, 24.9% (24.6%/0.3%), and 1.7% (1.5%/0.2%), respectively. Group L and Group C significantly differed in postoperative hematoma rate (0.0% vs. 1.8%, respectively; p = 0.0026) and in postoperative hypocalcemia rate (20.1% vs. 30.0%, respectively; p = 0.0032). The incidence of RLN palsy did not significantly differ between Group L and Group C (1.38% vs. 2.08%; p = 0.2652). The overall surgical complication rates are low in neuro-monitored thyroidectomy. The LSJ is feasible for performing completely sutureless thyroidectomy and obtains superior outcomes of postoperative hematoma and hypocalcemia in comparison with clamp-and-tie hemostatic technique. The novel LSJ technique using double or overlapped sealing is useful for sutureless thyroidectomy. However, surgeons must carefully observe the tissue contraction that may reduce the LSJ-RLN distance and increase the risk of thermal injury during the LSJ activation.

Prognostic Indicators of Non-Transection Nerve Injury and Vocal Fold Motion Impairment After Thyroid Surgery - Correlation Between Intraoperative Neuromonitoring Findings and Perioperative Voice Parameters

OBJECTIVES

In patients with recurrent laryngeal nerve (RLN) injury after thyroid surgery, unrecovered vocal fold motion (VFM) and subjective voice impairment cause extreme distress. For surgeons, treating these poor outcomes is extremely challenging. To enable early treatment of VFM impairment, this study evaluated prognostic indicators of non-transection RLN injury and VFM impairment after thyroid surgery and evaluated correlations between intraoperative neuromonitoring (IONM) findings and perioperative voice parameters.

METHODS

82 adult patients had postoperative VFM impairment after thyroidectomy were enrolled. Demographic characteristics, RLN electromyography (EMG), and RLN injury mechanism were compared. Multi-dimensional voice program, voice range profile and Index of voice and swallowing handicap of thyroidectomy (IVST) were administered during I-preoperative; II-immediate, III-short-term and IV-long-term postoperative periods. The patients were divided into R/U Group according to the VFM was recovered/unrecovered 3 months after surgery. The patients in U Group were divided into U1/U2 Group according to total IVST score change was <4 and ≥4 during period-IV.

RESULTS

Compared to R Group (42 patients), U Group (38 patients) had significantly more patients with EMG >90% decrease in the injured RLN (p<0.001) and thermal injury as the RLN injury mechanism (p=0.002). Voice parameter impairments were more severe in U Group compared to R Group. Compared to U1 group (19 patients), U2 Group (19 patients) had a significantly larger proportion of patients with EMG decrease >90% in the injured RLN (p=0.022) and thermal injury as the RLN injury mechanism (p=0.017). A large pitch range decrease in period-II was a prognostic indicator of a moderate/severe long-term postoperative subjective voice impairment.

CONCLUSION

This study is the first to evaluate correlations between IONM findings and voice outcomes in patients with VFM impairment after thyroid surgery. Thyroid surgeons should make every effort to avoid severe type RLN injury (e.g., thermal injury or injury causing EMG decrease >90%), which raises the risk of unrecovered VFM and moderate/severe long-term postoperative subjective voice impairment. Using objective voice parameters (e.g., pitch range) as prognostic indicators not only enables surgeons to earlier identify patients with low voice satisfaction after surgery, and also enable implementation of interventions sufficiently early to maintain quality of life.

Hyper-viscoelastic mechanical behavior of cranial pia mater in tension

BACKGROUND

Cranial pia mater, the innermost layer of the meninges, protects the central nervous system by tightly wrapping the brain and damping the external impact force to the brain. Accurate experimental data of the mechanical property of the cranial pia mater can enhance the theoretical prediction of traumatic brain injury or the scientific surgery design for brain disease. The aim of this study is to characterize the mechanical behavior of the cranial pia mater.

METHODS

In vitro tensile and stress-relaxation experiments of ovine cranial pia mater specimens were conducted at eight strain rates to characterize the rate-dependent viscoelastic property. The tensile and stress-relaxation experimental data were fitted by an Ogden hyper-viscoelastic model with a strain rate function to describe the mechanical behavior of the cranial pia mater.

FINDINGS

The elastic modulus and the ultimate stress are significantly increased from 5.545 MPa and 0.535 MPa at 0.00167 s^-1 to 18.345 MPa and 2.547 MPa at 0.83 s^-1 (p < .0001), respectively. The initial stress and the long-term stress (300 s) are also increased significantly with the increasing strain rates (p < .0001). A good fit of the experimental data with the Ogden hyper-viscoelastic model incorporated with a strain rate function was achieved (R² > 0.93).

INTERPRETATION

The cranial pia mater exhibits as a rate-dependent hyper-viscoelastic material in the tensile and stress-relaxation experiments. Compared with the brain, the stiffer nature of the cranial pia mater indicates its essential role in brain protection. The rate-dependent constitutive model provides a proper description of the hyper-viscoelastic characteristics of the cranial pia mater in tension and may provide a basic constitutive relationship for numerical simulations of traumatic brain injury.

CYP26A1 Is a Novel Biomarker for Betel Quid-Related Oral and Pharyngeal Cancers

Betel quid (BQ) has been classified as a Group I human carcinogen in light of evidence demonstrating an association with an elevated risk of oral and pharyngeal cancers. To date, the incidence rate of oral and pharynx cancers among Taiwanese men ranks the highest worldwide. However, no study has yet confirmed variants of CYP26A1 was associated with the risks of oral and pharyngeal cancers. A case-control study was conducted (n = 339). CYP26A1 polymorphism was performed using SNP assay. Real-time qRT-PCR and Western blotting were used to determine the levels of CYP26A1 expression. The cancer cell model involved treatment with arecoline. Our findings showed that the downregulation of CYP26A1 mRNA and protein expression are more frequently observed in cancerous tissues than adjacent normal tissues in patients with oral and pharynx cancers (p < 0.01). We found that CYP26A1 was downregulated as the arecoline dose increased. We hypothesized that lower levels of CYP26A1 mRNA expression can be utilized a clinically biomarker causes oral and pharynx cancers. Arecoline appears to modulate CYP26A1 expression through specific pathways. Carriers of CYP26A1 SNP, rs2068888 (G/G)/rs4418728 (G/G) and who have lower levels of CYP26A1 expression are associated with an increased risk of oral and pharyngeal cancers.

Full percutaneous intraoperative neuromonitoring technique in remote thyroid surgery: Porcine model feasibility study

BACKGROUND

In remote thyroid surgery, a reliable intraoperative neuromonitoring (IONM) procedure is an important tool for reducing injury to recurrent laryngeal nerve (RLN). This study proposes an alternative or adjunct technique for performing full percutaneous (PC) IONM and confirms its feasibility in animal experiments.

METHODS

This prospective porcine model study enrolled four piglets with eight nerve sides. Evoked electromyography (EMG) was stimulated from PC ball-tip probe, and recorded from EMG endotracheal tube (ETT) and from PC paired long-needle electrodes on the perichondrium of the lateral aspect of thyroid cartilage.

RESULTS

In all RLNs and vagus nerves, typical laryngeal EMG waveforms were successfully evoked by PC probe stimulation and recorded by both ETT and PC needle electrodes.

CONCLUSIONS

This study confirms the feasibility of the full PC IONM techniques in porcine model. However, further clinical studies are needed to compare the practicality of different remote-access approaches for thyroid surgery.

Precision Neuromuscular Block Management for Neural Monitoring During Thyroid Surgery

INTRODUCTION

Titration of neuromuscular block (NMB) plays a key role in intraoperative recurrent laryngeal nerve monitoring during thyroid surgery. The combination of neuromuscular blocking agent and timely partial reversal of NMB was investigated in both animal experiments and clinical neuro-monitored thyroidectomy.

METHODS

In animal experiments, 8 piglets received sugammadex to assess the laryngeal EMG recovery after rocuronium-induced NMB. In clinical monitored thyroidectomy, 40 patients each were allocated to conventional group and sugammadex group. Conventional group received rocuronium 0.3 mg/kg at anesthesia induction, while sugammadex group received partial NMB recovery protocol- 0.6 mg/kg of rocuronium at anesthesia induction and 0.5 mg/kg of sugammadex. Main outcome was assessed by first (V1) and final (V2) EMG signal induced by vagal stimulation.

RESULTS

In the porcine model, 50% recovery of laryngeal EMG amplitude was achieved at 16.8 ± 1.9 and 6 ± 2.7 minutes respectively after 0.5 and 1 mg/kg of sugammadex (p < 0.01). In monitored thyroidectomy, EMG amplitudes at V1 in group S and group C were 1214 ± 623 and 915 ± 476 μV, respectively (p = 0.02). Positive and adequately high EMG amplitudes were observed at the early surgical stage for all patients. Sugammadex groups were superior to conventional group in EMG tube placement (p < 0.001).

CONCLUSION

Both porcine model and clinical application showed that precise NMB management by low-dose sugammadex was effective for intraoperative neural monitoring (IONM). The regimen ensured optimal conditions for tracheal intubation and timely neuromuscular function restoration for high-quality EMG signal.

Neural Monitoring of the External Branch of the Superior Laryngeal Nerve During Transoral Thyroidectomy

OBJECTIVES/HYPOTHESIS

There is no study regarding intraoperative neural monitoring (IONM) of the external branch of the superior laryngeal nerve (EBSLN) during transoral thyroidectomy. The objective of this study was to evaluate the feasibility and success rate of electrical identification of the EBSLN during transoral robotic or endoscopic thyroidectomy.

STUDY DESIGN

Case series study.

METHODS

We studied a cohort of 76 patients (87 nerves at risk, (NARs)) who underwent transoral robotic or endoscopic thyroidectomy and simultaneous intermittent IONM between July 2017 and May 2019. We performed the standard IONM procedure plus routine neural monitoring of the EBSLN. IONM and surgical outcome data were prospectively collected.

RESULTS

Sixty-one patients underwent the robotic procedure, and 15 patients underwent the endoscopic procedure. Thirty-seven external branches of the superior laryngeal nerves at risk (42.5%) were electrically identified using electromyography signals (31 NARs, 35.6%) or cricothyroid muscle twitches (6 NARs, 6.9%). The mean pre-(S1) and post-dissection (S2) amplitudes of the EBSLN were 372 ± 147 and 351 ± 159 μV, respectively. The identification rates were not different between the robotic and endoscopic procedures. In comparing the early 20 NARs (18 patients) and the later 67 NARs (58 patients), the identification rate was higher in the later cases, although the difference was not statistically significant (25.0% vs. 47.8%, P = .079).

CONCLUSION

IONM of the EBSLN is feasible and useful in identifying and preserving the nerve during transoral thyroidectomy, although the identification rate of the nerve is relatively low.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E671-E676, 2021.

Safety parameters of ferromagnetic device during thyroid surgery: Porcine model using continuous neuromonitoring

BACKGROUND

The ferromagnetic (FM) device is a new surgical energy modality. This study investigated dynamic recurrent laryngeal nerve (RLN) electromyographic (EMG) data to define safety parameters for using FM devices in thyroidectomy.

METHODS

Real-time EMG tracings obtained under continuous neuromonitoring were recorded from 24 RLNs (12 piglets). In the activation study, FM devices were activated at varying distances from the RLN. In the cooling study, FM devices were cooled for varying time intervals, or muscle touch maneuver was performed, before contact with the RLN.

RESULTS

During the FMwand/FMsealer activation, no adverse EMG events occurred at distances of 2 mm or longer. The cooling study revealed no adverse EMG events after 1-second (FMwand) or 3-second (FMsealer) intervals or after muscle touch maneuver.

CONCLUSIONS

An FM device should be activated at a distance of 2 mm from the RLN and should be adequately cooled before further contact with the RLN. Surgeons can avoid RLN injury by observing standard procedures for using FM devices.

Safety of Ligasure exact dissector in thyroidectomy with continuous neuromonitoring: a porcine model

Background

The purpose of this study was to investigate and define safety parameters for using the Ligasure exact dissector (LED) for dissection close to the recurrent laryngeal nerve (RLN) during thyroidectomy.

Methods

Real-time electrophysiologic electromyographic (EMG) tracings were recorded in 16 RLNs (8 piglets) during various applications of LED under continuous intraoperative monitoring in this prospective porcine model study. In the activation study, LED was activated at varying distances from the RLN. In the cooling study, LED was activated with different cooling times or after touching the sternocleidomastoid muscle before application to the RLN.

Results

In the activation study, no adverse EMG events occurred at distances longer than 1 mm. In the cooling study, no adverse EMG events occurred after a 2-second cooling time. Additionally, no adverse EMG events occurred when a sternocleidomastoid muscle touch maneuver was used for cooling.

Conclusions

The LED can be safely used at distance of 1 mm or longer, and it should be cooled for at least 2 seconds or by muscle touch maneuver. Thyroid surgeons can avoid RLN injury if standard procedures for LED use are observed.

Prognosis and clinicopathologic features in patients with gastric stump cancer after curative surgery

Background

Gastric stump ("remnant") cancer is the development of a malignancy related to previous gastric surgery. Prognosis in gastric stump cancer, compared with that in primary gastric cancer, is still controversial.

Methods

From January 1988 to December 2012 at a single medical centre in Taiwan, 105 patients with gastric stump cancer, including 85 with previous peptic ulcer disease and 20 with previous gastric cancer, were analyzed for clinicopathologic characteristics and overall survival (os).

Results

The 5-year os rates for patients with gastric stump cancer and with primary gastric cancer were 51.2% and 54.5% respectively (p = 0.035). Analysis of clinicopathologic characteristics indicated that, compared with patients having primary gastric cancer, those with gastric stump cancer had more lymph node metastasis (p < 0.001) and had been diagnosed at a more advanced stage (p = 0.047). Multivariate analysis with os as an endpoint showed that age [p = 0.015; hazard ratio (hr): 2.300; 95% confidence interval (ci): 1.173 to 4.509], tumour size (p = 0.037; hr: 1.700; 95% ci: 1.031 to 2.801), stromal reaction (p = 0.021; hr: 1.802; 95% ci: 1.094 to 2.969), and pathologic N category (p = 0.001; hr: 1.449; 95% ci: 1.161 to 1.807) were independent predictors in gastric stump cancer. The os rates for patients with gastric stump cancer who previously had gastric cancer or peptic ulcer disease were 72.9% and 50.0% respectively (p = 0.019). The Borrmann classification was more superficial (p = 0.005), lymph node metastases were fewer (p = 0.004), and staging was less advanced (p = 0.025) in patients with gastric stump cancer who previously had gastric cancer than in their counterparts who previously had peptic ulcer disease.

Conclusions

Survival is poorer in patients with gastric stump cancer who previously had peptic ulcer disease than in those who previously had primary gastric cancer. Patients with gastric stump cancer who previously had gastric cancer and could receive curative gastrectomy tended to have a better prognosis because of a more superficial Borrmann classification. Regular follow-up in patients who have undergone gastric surgery is recommended for the early detection of gastric stump cancer.

Peculiar anatomic variation of recurrent laryngeal nerve and EMG change in a patient with right substernal goiter and pre-operative vocal cord palsy-case report

We report a patient with right substernal goiter and preoperative vocal cord palsy (VCP). During dissection, an anatomic variation of the recurrent laryngeal nerve (RLN) and a prolonged EMG were detected by intraoperative neuromonitoring (IONM). Symmetrical vocal cord movement was recorded one month after surgery. The potential for recovery of vocal cord function is high after surgical treatment of a thyroid tumor with preoperative VCP. An IONM enables early localization of the RLN position. To the best of our knowledge, this case of prolonged EMG in an abnormal acquired-ventral RLN trajectory is the first reported in the literature.

U-shaped strap muscle flap for difficult thyroid surgery

Background

Open thyroidectomy via conventional midline approach can be challenging in complex thyroid surgeries. This study proposes a U-shaped strap muscle flap (USMF) technique that provides adequately wide exposure of the surgical field.

Methods

Strap muscles were cut close to the clavicle and along the anterior margin of both sternocleidomastoid muscles followed by total thyroidectomy in 20 patients as USMF group, and surgical outcomes were compared with 40 patients who had received total thyroidectomy via midline approach.

Results

No patient had postoperative hematoma, vocal cord paralysis, permanent hypocalcaemia, wound infection or flap necrosis. At 2 months post-surgery, objective voice analysis and subjective assessment of voice and swallowing showed no significant difference between groups.

Conclusions

USMF provides superb surgical field exposure, and the voice and swallowing functions after USMF are comparable to those obtained by midline approach. The USMF approach is a feasible option for selective difficult thyroid surgery.